The Nielsen Company says an estimated 20.6 million people watched Obama's inauguration, held in Washington, D.C. It's a steep decline from the audience for the 2009 inauguration: 37.8 million.

Eighteen networks offered live coverage of the inauguration at some point between 10 a.m. and 4:30 p.m. Eastern time.

For the week ending Sunday, the NFL playoffs ruled the ratings. CBS' telecast of the AFC Championship Game between the victorious Baltimore Ravens and the New England Patriots attracted 47.7 million viewers.

Fox's coverage of the NFC Championship Game, in which the San Francisco 49ers defeated the Atlanta Falcons, was seen by 42 million people on Sunday afternoon.

CBS won the primetime network ratings race for the week, followed by Fox, ABC, Univision, NBC, the CW, Telemundo and ION Television.

Here are the top 10 primetime programs for the week of January 14-20, according to the Nielsen Company: